Pimavanserin use in a movement disorders clinic: a single-center experience

Parkinson's disease psychosis (PDP) is a disabling non-motor symptom of Parkinson's disease (PD) that is challenging to treat. Dopamine receptor blockers (DRB) are used to treat PDP, though these may be associated with adverse effects, including worsening of Parkinsonism. Pimavanserin, a selective 5-HT_2A receptor inverse agonist, was recently FDA-approved for treatment of PDP; however, there is limited information on its long-term use in PDP patients.

A retrospective chart review of patients prescribed pimavanserin was performed in August, 2017. Data on demographics, psychotic features, sleep, and adverse effects was collected using a semi-structured telephone interview with patients or caregivers. Hallucination severity (HS) was quantified as mild (< 1 episode/week), moderate (1/week to < 1/day), or severe (daily/continuous).

Seventeen patients consented to participate in the study; 16 were diagnosed with PDP, 1 with Lewy body dementia. Fourteen had co-morbid cognitive impairment/dementia. The mean duration of Parkinsonism was 11.8 ± 8.0 years, with 2.6 ± 1.9 years of psychosis. Eleven of the seventeen patients reported improvement of hallucinations of which 5/8 were initiated on pimavanserin monotherapy, and 6/9 reported improvement of HS with combination of DRB. Six of nine patients prescribed DRB were able to discontinue this medication after introduction of pimavanserin. Four patients discontinued medications (2, no benefit; 1, spontaneous resolution; 1, cost). No major side effects were reported, and two patients noted subjective improvement of sleep.

In our series based on a small sample size, pimavanserin is well-tolerated and effective as both monotherapy and adjuvant treatment for moderate to severe. This medication can facilitate reduction or cessation of DRB medication.